Re: [Firebird-devel] User semantics vs authentication

[Aleksey K. <kar...@cm...>]

Hi!

"Jim Starkey" <ja...@ne...> wrote in message 
news:415...@ne......
>
>
> This question has been around longer than Interbase.  The great unwritten 
> component is traditionally called the mega-database manager.

Why unwritten ? I thought there are lots of Mega Database Managers on the 
market. Most "big" DBMS have such capability not counting separate products.

> The MDM is a provider (using Vulcan terminology) in which virtual 
> databases are defined from a number of physical databases.  The MDM 
> manages virtual metadata, decomposes queries to underlaying databases, 
> optimizes semi-joins, and generally acts as traffic cop.  In the grand 
> scheme of things, handling target database account information is a 
> necessary but relative simple task of the MDM.
>
> The only things that has held back development of the mega-database 
> manager have been time and money.  If anyone out there has the money, I'll 
> be happy the find the time...

What's the difference between performing a join (for example) using two 
tables in the single database or from the separate database files on the 
same Firebird server ? Two tables are just objects loaded in server memory 
at some point.

One difference is 2PC protocol because different databases have their 
separate transaction models (own transaction log / back record version 
chain). But 2PC isn't worth considering as requiring too much money (and 
time) to implement ...

Regards,
Aleksey Karyakin

> -- 
>
> Jim Starkey
> Netfrastructure, Inc.
> 978 526-1376
>